如何添加元素（或将Integer ArrayList转换为Integer Array）

Question

here is what i have got

ArrayList<Integer> list = new ArrayList<Integer>();
    Integer a = 50; 
    Integer b = 55;
    Integer c = 98;
    Integer d = 101;
    list.add(a);
    list.add(b);
    list.add(c);
    list.add(d);

now i want to convert this "list" to an Array... eg:

Integer[] actual= {50,55,98,101};

anyway how to do it? thanks.

Answer 1

Integer[] array = list.toArray(new Integer[list.size()]);

If you want an int[] array, you'll have to loop over the list and unbox each element explicitly.

See http://download.oracle.com/javase/6/docs/api/java/util/List.html next time you're looking for a method of List.

Answer 2

Sefirosu, for another solution you can do it using Arrays.copyOf() or Arrays.copyOfRange() too.

Integer[] integerArray = Arrays.copyOf(list.toArray(), list.toArray().length, Integer[].class);
Integer[] integerArray = Arrays.copyOfRange(list.toArray(), 0, 4, Integer[].class);